MI5 carried out secret mass surveillance for a decade | Ars Technica MI5 has been secretly collecting vast quantities of data about UK phone calls for the last 10 years. According to a report on BBC News, the newly-revealed programme was "so secret that few even in MI5 knew about it, let alone the public." Meanwhile, as part of GCHQ's continuing charm offensive to bolster the case for wider surveillance powers, a senior officer named "Peter" has taken the unusual step of writing an article in The Guardian.